Cold dark matter model (CDM) is an extremely successful model to explain the large scale structure of the Universe, corresponding to distances greater than O(Mpc) today. However, some numerical simulations indicate that observations connected with small scales might be in tension with this framework. In particular, simulations based on CDM show that the mass density profile of CDM halo increases as 1/r toward the center, whereas many observed rotation curves of disk galaxies prefer a constant cored density profile. CDM also predicts a greater number of galactic satellites than observed. Observations also show that galactic clusters have mass deficit in the inner O(10) kpc region. In this talk I will present a model in which the dark matter particle is a fermion with a mass around 100 eV, the relic density is generated from the freeze-in mechanism. I will show that in this model the above small scale anomalies can be automatically solved.